Zechariah 12:4

I will smite every horse of those gathered there with bewilderment and blindness, and their riders with madness (Shem Ephraim). But upon the [members of the] house of Judah, who are among those gathered against their will, I will open My eyes to protect them from this plague.

"And on that day, in that great war, I will strike every horse with confusion and its rider with madness" — meaning that those who come to besiege Jerusalem, neither they nor their horses will act in an orderly manner during the battle. The horses will be in confusion, without courage, and the riders will act like madmen, without reason, but in panic, without understanding. "And upon the house of Judah I will open My eyes" — meaning that God will protect those who are sitting in siege within Jerusalem, saving them from the hands of their enemies who are besieging them. Rashi and the Ibn Ezra explained "upon the house of Judah I will open My eyes" to mean that even though they are coming with those who are besieging Jerusalem, God will protect them so that they will not suffer the same harm and destruction that will come upon the besieging forces. Additionally, it is mentioned that God will perform another miracle: every horse from those who come to besiege Jerusalem will be struck with blindness, so that none of them will see where they are going or to which side they will fight.